Isoxazolopyridinones

ABSTRACT

The invention provides compounds of formula I, wherein X, Y, R 1 , R 2 , and R 3  are as defined in the description, and the preparation thereof. The compounds of formula I are useful as pharmaceuticals.

The present invention relates to novel isoxazolopyridinone derivatives,their preparation, their use as pharmaceuticals and pharmaceuticalcompositions containing them.

The invention provides compounds of formula I

wherein

-   either X is O and Y is N or X is N and Y is O,-   R₁ is hydrogen, C₁₋₄alkyl, C₃₋₇cycloalkyl, C₃₋₇cycloalkyl-C₁₋₄alkyl    or di-C₁₋₄alkylamino-C₁₋₄alkyl,-   R₂ is C₁₋₄alkyl, C₃₋₇cycloalkyl, benzo [1,3]dioxol-5-yl,    benzo[1,2,5]oxadiazol-5-yl, benzo[1,2,5]thiadiazol-5-yl or a group    of formula (a)

-   -   wherein Z is CH or N, R₄ is hydrogen, C₁₋₄alkyl, C₁₋₄alkoxy,        halogen, hydroxy, trifluoromethyl, di-C₁₋₄alkylamino,        C₁₋₄alkylamino, di-C₁₋₄alkylamino-C₁₋₄alkyl,        C₁₋₄alkylamino-C₁₋₄alkyl, di-C₁₋₄alkylamino-C₁₋₄alkoxy,        C₁₋₄alkylamino-C₁₋₄alkoxy,        di-C₁₋₄alkylamino-C₁₋₄alkoxy-C₁₋₄alkyl,        C₁₋₄alkylamino-C₁₋₄alkoxy-C₁₋₄alkyl,        di-(C₁₋₄alkoxy-C₁₋₄alkyl)amino,        di-(C₁₋₄alkoxy-C₁₋₄alkyl)amino-C₁₋₄alkyl, phenyl, phenoxy,        benzyloxy C₁₋₄alkyl, C₁₋₄alkoxy-C₁₋₄alkyl,        C₁₋₄alkoxy-C₁₋₄alkoxy-C₁₋₄alkyl, hydroxy-C₁₋₄alkyl, CHO,        carboxy, C₁₋₄alkoxycarbonyl, morpholinomethyl,        4-C₁₋₄alkyl-piperazinylmethyl, piperazinylmethyl,        tetrazol-1-ylmethyl, 1-pyrrolylmethyl,        3-(di-C₁₋₄-alkylamino-2-hydroxy-propoxy-C₁₋₄alkyl,        3-(di-C₁₋₄-alkylamino-2-hydroxy-propoxy,        3-C₁₋₄-alkylamino-2-hydroxy-propoxy-C₁₋₄alkyl,        3-C₁₋₄-alkylamino-2-hydroxy-propoxy,        2-hydroxy-3-imidazol-1-yl-propoxy-C₁₋₄alkyl,        2-hydroxy-3-imidazol-1-yl-propoxy,        2-hydroxy-3-morpholin-4-yl-propoxy,        2-hydroxy-3-morpholin-4-yl-propoxy-C₁₋₄alkyl, and R₅ and R₆,        independently, are hydrogen, halogen, hydroxy, C₁₋₄alkyl or        C₁₋₄alkoxy, and

-   R₃ is hydrogen, halogen, C₁₋₄alkyl, di-C₁₋₄alkylamino-C₁₋₄alkyl,    di-C₁₋₄alkylamino-C₁₋₄alkoxy, C₁₋₄alkylamino-C₁₋₄alkyl,    C₁₋₄alkylamino-C₁₋₄alkoxy or C₁₋₄alkoxy,    in free base or pharmaceutically acceptable acid addition salt form,    for use in the treatment of Parkinson's disease.

Any alkyl or alkoxy group as defined above preferably has one or twocarbon atoms and more preferably is methyl or methoxy.

Halogen denotes fluorine, chlorine or bromine.

In a further aspect, the invention provides a process for the productionof the compounds of formula I and their salts, comprising the step ofreacting a compound of formula II

wherein R₁ and R₃ are as defined above, with a compound of formula IIIR₇—R₂  IIIwherein R₂ is as defined above and R₇ is CHO, CN, CO-Hal, wherein Hal ishalogen, CON(CH₃)—OCH₃ or morpholinocarbonyl.

The reaction can be effected according to known methods, for example asdescribed in Example 1 b).

Compounds of formula I wherein R₂ is a group of formula (a) wherein R₄is di-C₁₋₄ alkylaminomethyl, C₁₋₄alkoxymethyl,di-C₁₋₄alkylamino-C₂₋₄alkoxymethyl, C₁₋₄alkoxy C₂₋₄alkoxymethyl,morpholinomethyl, piperazinylmethyl, 4-C₁₋₄alkylpiperazinylmethyl,tetrazol-1-ylmethyl or 1-pyrrolylmethyl, can also be produced from thecorresponding compounds wherein R₄ is methyl, by bromination followed bynucleophilic substitution, according to conventional procedures, e.g. asdescribed in Example 29.

Working up the reaction mixtures and purification of the compounds thusobtained may be carried out in accordance to known procedures.

Acid addition salts may be produced from the free bases in known manner,and vice-versa.

The starting compounds of formula II may be produced from carboxylicacids of formula IV

wherein X, Y and R₃ are as defined above, according to known procedures,e.g. as described in Example 1a).

The starting materials of formulae III and IV are known or may beproduced in analogous manner to known procedures.

Compounds of formula I and their pharmaceutically acceptable acidaddition salts, hereinafter referred to as agents of the invention,exhibit valuable pharmacological properties where tested in vitro usingNurr1 expressing cell cultures and in vivo, and are therefore useful aspharmaceuticals.

The nuclear receptor Nurr1 is known to be causally involved in thefunctional differentiation of midbrain dopaminergic neurones both duringdevelopment and in adult animals. The defects of dopaminergic neuronesobserved in the ventral midbrain of Nurr1 knockout animals resemble thepattern of neuronal degeneration in Parkinson's disease, in which theprimary motor defects are caused by the degeneration of the substantianigra dopaminergic system (Zetterström et al., 1997; Castillo et al.,1998 and Saucedo-Cardenas et al., 1998). Nurr1 activators are thereforesuggested for preventing or delaying the onset of Parkinsonian symptoms.

The affinity of the agents of the Invention to the Nurr1 receptor can bedetermined in vitro in binding studies:

Two-dimensional ¹H-¹⁵N correlated spectra (HSQC) are recorded ofuniformly ¹⁵N-labeled ligand binding domain (LBD) of Nurr1 expressed inE. Coli. The spectra provide a fingerprint of the protein structure andchanges in the exact positions of some of the cross peaks in the 2-dspectrum upon titration of a compound indicate ligand binding.

In this assay, changes in chemical shift are observed in some peaks atconcentrations of 300 μM of the agent of the invention, using 50 μMuniformly ¹⁵N-labeled Nurr1 LBD.

The activity of the agents of the invention at the Nurr1 receptor can bedetermined in vitro in cellular assays:

Induction of the biological activity of the Nurr1 receptor by the agentsof the invention can be measured by the transactivation of a Nurr1responsive reporter gene in a midbrain dopaminergic cell line. The assayis based on the transcription promoting effect of Nurr1. The reportergene can be activated both by Nurr1 monomers and Nurr1/RXR heterodimers.RXR is a frequent heterodimerisation partner of nuclear receptors and ithas been shown that Nurr1 can form heterodimers with RXR (Zetterström RHet al. Mol. Endocrinol. 1996; 10:1656–1666).

In this assay the agents of the invention significantly increase thereporter gene activity dose dependently at EC₅₀s of about 1 to about 100nM.

In vivo, the agents of the invention significantly increase midbraindopamine levels at doses of 5 to 30 mg/kg p.o. in the following assay:

OF1 mice are treated with the test compound for five days and sacrificed5 hours after the last compound application. Dopamine levels aremeasured in substantia nigra and striatal tissue punches. 10 animals aretreated in each group.

The agents of the invention are therefore useful in the treatment ofParkinson's disease.

For the above-mentioned indication, the appropriate dosage will ofcourse vary depending upon, for example, the compound employed, thehost, the mode of administration and the nature and severity of thecondition being treated. However, in general, satisfactory results inanimals are indicated to be obtained at a daily dosage of from about 0.1to about 500, preferably from about 0.5 to about 100 mg/kg animal bodyweight. In larger mammals, for example humans, an indicated daily dosageis in the range from about 1 to about 500, preferably from about 1 toabout 300 mg of an agent of the invention, conveniently administered,for example, in divided doses up to four times a day or in sustainedrelease form.

The agents of the invention may be administered in free form or inpharmaceutically acceptable salt form. Such salts may be prepared inconventional manner and exhibit the same order of activity as the freecompounds.

The agent of the invention may be administered by any conventionalroute, in particular enterally, preferably orally, for example in theform of tablets or capsules, or parenterally, for example in the form ofinjectable solutions or suspensions.

The agents of the invention may alternatively be administered e.g.topically in the form of a cream, gel or the like, or by inhalation,e.g. in dry powder form.

Examples for compositions comprising an agent of the invention include,e.g. a solid dispersion, an aqueous solution, e.g. containing asolubillising agent, a microemulsion and a suspension of an agent of theinvention. The composition may be buffered to a pH in the range of e.g.from 3.5 to 9.5, by a suitable buffer.

The agents of the invention can be administered either alone or incombination with other pharmaceutical agents effective in the treatmentof Parkinson's disease.

Thus, the agents of the invention can be used for the treatment ofParkinson's disease in combination with, for example, dopamineprecursors (e.g. different levodopa preparations), dopamine agonists(e.g. Bromocriptine, Pramipexole), catechol-O-methyltransferaseinhibitors (e.g. Entacapone, Tolcapone), monoamine oxidase B inhibitors(e.g. Selegiline), NMDA antagonists (e.g. Amantadine) andanticholinergics (e.g. Biperiden, Orphenedrine).

In accordance with the foregoing, the present invention also providesthe use of an agent of the Invention, for the manufacture of amedicament for the treatment of Parkinson's disease.

The preferred agents of the invention include6-(4-dimethylaminomethyl-phenyl)-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-oneand6-[4-(2-methoxy-ethoxymethyl)-phenyl]-5-methyl-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one,in free base or pharmaceutically acceptable acid addition salt form.

In the above-mentioned in vitro cellular assay, these compounds increasethe reporter gene activity with EC₅₀s of 70 and 40 nM respectively. Inthe above-mentioned in vivo test, they increase the dopamine levels byabout 20–30% on administration of 5, 10 and 30 mg/kg p.o.

In still a further aspect, the invention provides compounds of formula Iwherein X, Y, R₁, R₂ and R₃ are as defined above, provided that

-   i) when X is N, Y is O, R₂ is unsubstituted phenyl and R₃ is    hydrogen, then R₁ is different from hydrogen, and-   ii) when X is N, Y is O, R₂ is a group of formula (a) wherein either    Z is N and R₄ is hydrogen, or Z is CH and R₄ is hydrogen, methyl,    methoxy, halogen, trifluoromethyl, p-bromomethyl, p-benzyloxy,    dimethylaminomethyl, methylaminomethyl, 4-C₁₋₄alkylpiperazinomethyl,    piperidinomethyl or morpholinomethyl and R₃ is hydrogen, chlorine,    fluorine, methyl, trifluoromethyl or C₁₋₄alkoxy, then R₁ is    different from methyl,    hereinafter referred to as novel compounds of formula I.

The present invention furthermore provides a pharmaceutical compositioncomprising a novel compound of formula I in free base orpharmaceutically acceptable acid addition salt form, in association withat least one pharmaceutical carrier or diluent. Such compositions may bemanufactured in conventional manner. Unit dosage forms contain, forexample, from about 0.25 to about 150, preferably from 0.25 to about 25mg of the compound.

The pharmaceutical compositions for separate administration of thecombination partners and for the administration in a fixed combination,i.e. a single galenical composition comprising at least two combinationpartners according to the invention, can be prepared in a manner knownper se and are thus suitable for enteral, such as oral or rectal, andparenteral administration to mammals, including man, comprising atherapeutically effective amount of at least one pharmacologicallyactive combination partner alone or in combination with one or morepharmaceutically acceptable carriers, especially suitable for enteral orparenteral application.

In particular, a therapeutically effective amount of each of thecombination partners may be administered simultaneously or sequentiallyand in any order, and the components may be administered separately oras fixed combination.

Accordingly the invention also provides a combination comprising atherapeutically effective amount of a novel compound of formula I infree base or pharmaceutically acceptable acid addition salt form and asecond drug substance, said second drug substance being for example foruse in Parkinson's disease.

Moreover the present invention provides the use of a novel compound offormula I in free base or pharmaceutically acceptable acid addition saltform, as pharmaceutical for the treatment of Parkinson's disease.

In still a further aspect the present invention provides a method forthe treatment of Parkinson's disease in a subject in need of suchtreatment, which comprises administering to such subject atherapeutically effective amount of a novel compound of formula I infree base or pharmaceutically acceptable acid addition salt form.

The following examples illustrate the invention.

EXAMPLE 15-Methyl-6-[4-(4-methyl-piperazin-1-ylmethyl)-phenyl]-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-onea) 5-Methyl-3-phenyl-isoxazole-4-carboxylic acid methylamide

To a suspension of 50.0 g (0.25 mol) of5-methyl-3-phenyl-isoxazole-4-carboxylic acid in 1.2 l of1,2-dichloroethane (DCE) is added 1.9 ml dimethyl formamide (DMF) and21.4 ml (0.3 mol, 1.2 eq.) of thionyl chloride. The mixture is stirredfor 2 h at reflux until a clear, yellow solution is formed. The solutionis cooled to room temperature and then slowly added to a 8M solution ofmethylamine in ethanol (146 ml) at 5° C. The suspension is poured ontomethylene chloride, washed with sat. NaHCO₃-solution, dried over Na₂SO₄and concentrated. This yields 52.3 g (99%) of the title compound aslight brown solid, which is used for further reaction withoutpurification. Mass spectrum: m/z (M+H)⁺: 217.1

b)5-Methyl-6-[4-(4-methyl-piperazin-1-ylmethyl)-phenyl]-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one

In a 500 ml flask, 10.0 g (46.3 mmol) of5-methyl-3-phenyl-isoxazole-4-carboxylic acid methylamide is suspendedin 150 ml of tetrahydrofuran (THF) under argon. At −70° C. a solution ofbutyl lithium (63 ml, 1.6M in hexane, 101 mmol, 2.2 eq.) is slowlyadded. After 1 h at this temperature, the solution is warmed to −10° C.and a solution of 11.9 g (55.5 mmol, 1.2 eq.) of4-(4-methyl-piperazin-1-ylmethyl)-benzonitrile in 80 ml of THF is slowlyadded. Under warming to room temperature, the red solution is stirredfor another hour, then quenched with 2 ml of water and concentrated. Theyellow residue is then taken up in 75 ml of dioxane and kept at 5° C.Then, 230 ml of a 4M solution of HCl in dioxane is carefully added andthe suspension stirred for 20 h at room temperature. Then, the solventis removed and the residue dissolved in ethyl acetate and carefullyneutralised with sat. NaHCO₃-solution. The phases are separated and theorganic phases washed with brine, dried over Na₂SO₄ and concentrated.Chromatographic purification (CH₂Cl₂/MeOH 95:5 to 90:10) yields 7.9 g(41%) of5-methyl-6-[4-(4-methyl-piperazin-1-ylmethyl)-phenyl]-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-oneas a white solid. Mass spectrum: m/z (M+H)⁺: 415.0

According to the procedure described for Example 1, using theappropriate nitrile or Weinreb Amide, the following compounds areprepared:

EXAMPLE 2

6-Benzo[1,3]dioxol-5-yl-5-methyl-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one:This compound is obtained using benzo[1,3]dioxole-5-carbonitrile in 56%as a light yellow solid. Mass spectrum: m/z (M+H)⁺: 347.2

EXAMPLE 3

6-Biphenyl-4-yl-5-methyl-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one: Thiscompound is obtained using biphenyl-4-carbonitrile in 11% as a whitefoam. Mass spectrum: m/z (M+H)⁺: 379.1

EXAMPLE 4

5-Methyl-3-phenyl-6-pyridin-4-yl-5H-isoxazolo[4,5-c]pyridin-4-one: Thiscompound is obtained using isonicotinonitrile in 59% as a pink solid.Mass spectrum: m/z (M+H)⁺: 304.1

EXAMPLE 5

6-(4-Diethylamino-phenyl)-5-methyl-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one:This compound is obtained using 4-diethylamino-benzonitrile in 11% as abeige solid. Mass spectrum: m/z (M+H)⁺: 374.1

EXAMPLE 6

5-Methyl-6-(4-phenoxy-phenyl)-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one:This compound is obtained using 4-phenoxy-benzonitrile in 44% as a beigesolid. Mass spectrum: m/z (M+H)⁺: 395.0

EXAMPLE 7

6-[4-(2-Methoxy-ethoxymethyl)-phenyl]-5-methyl-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one:This compound is obtained usingN-Methoxy-4-(2-methoxy-ethoxymethyl)-N-methyl-benzamide in 58% as awhite solid. Mass spectrum: m/z (M+H)⁺: 391.2

EXAMPLE 8

5-Methyl-3-phenyl-6-(4-tetrazol-1-ylmethyl-phenyl)-5H-isoxazolo[4,5-c]pyridin-4-one:This compound is obtained using 4-tetrazol-1-ylmethyl-benzonitrile andafter additional RP18-purification in 6% as a white solid. Massspectrum: m/z (M-N₂+H)⁺: 357.1

EXAMPLE 9

5-Methyl-3-phenyl-6-p-tolyl-5H-isoxazolo[4,5-c]pyridin-4-one: Thiscompound is obtained using 4-methyl-benzonitrile in 56% as a beigesolid. Mass spectrum: m/z (M+H)⁺: 317.1

EXAMPLE 9a

6-(3,4-Dimethoxy-phenyl)-5-methyl-3-phenyl-5H-isoxazolo[5-c]pyridin-4-one:This compound is obtained using 3,4-dimethoxy-benzonitrile in 11% as abeige solid. Mass spectrum: m/z (M+H)⁺: 363.1

EXAMPLE 9b

6-(3,5-Dimethoxy-phenyl)-5-methyl-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one:This compound is obtained using 3,5-dimethoxy-benzonitrile in 25% as ayellow resin. Mass spectrum: m/z (M+H)⁺: 363.1

According to the procedure described for Example 1, using acetylchlorideinstead of the nitrile, the following compound is prepared:

EXAMPLE 10 5,6-Dimethyl-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one: Massspectrum: m/z (M+H)⁺: 241.2

According to the procedure described for example 1, using theappropriate nitrile or Weinreb Amide,5-methyl-3-phenyl-isoxazole-4-carboxylic acid amide and 3.3 eq. of butyllithium, the following compounds are prepared:

EXAMPLE 11

6-(4-Dimethylaminomethyl-phenyl)-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one:This compound is obtained using 4-dimethylaminomethyl-benzonitrile in25% as a beige solid. Mass spectrum: m/z (M+H)⁺: 346.2

EXAMPLE 12

6-[4-(4-Methyl-piperazin-1-ylmethyl)-phenyl]-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one:This compound is obtained using4-(4-methyl-piperazin-1-ylmethyl)-benzonitrile in 13% as a solid. Massspectrum: m/z (M+H)⁺: 401.1

EXAMPLE 13

6-[4-(2-Methoxy-ethoxymethyl)-phenyl]-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one:This compound is obtained usingN-Methoxy-4-(2-methoxy-ethoxymethyl)-N-methyl-benzamide in 70% as awhite solid. Mass spectrum: m/z (M+H)⁺: 377.1

According to the procedure described for example 1, using theappropriate nitrile and 5-methyl-3-phenyl-isoxazole-4-carboxylic acidethylamide, the following compounds are prepared:

EXAMPLE 14

5-Ethyl-6-(3-methoxy-phenyl)-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one:This compound is obtained using 3-methoxy-benzonitrile in 28% as asolid. Mass spectrum: m/z (M+H)⁺: 347.2

EXAMPLE 15

6-Benzol[1,3]dioxol-5-yl-5-ethyl-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one:This compound is obtained using benzo[1,3]dioxole-5-carbonitrile in 10%as a solid. Mass spectrum: m/z (M+H)⁺: 361.2

According to the procedure described for example 1, using theappropriate nitrile and 5-methyl-3-phenyl-isoxazole-4-carboxylic acidpropylamide, the following compound is prepared:

EXAMPLE 16

3,6-Diphenyl-5-propyl-5H-isoxazolo[4,5-c]pyridin-4-one: This compound isobtained using benzonitrile in 49% as a solid. Mass spectrum: m/z(M+H)⁺: 331.2

According to the procedure described for example 1, using theappropriate nitrile and 5-methyl-3-phenyl-isoxazole-4-carboxylic acidcyclopropylamide, the following compounds are prepared:

EXAMPLE 17

5-Cyclopropyl-3,6-diphenyl-5H-isoxazolo[4,5-c]pyridin-4-one: Thiscompound is obtained using benzonitrile in 17% as a solid. Massspectrum: m/z (M+H)⁺: 329.2

EXAMPLE 18

6-Benzo[1,3]doxol-5-yl-5-cyclopropyl-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one:This compound is obtained using benzo[1,3]dioxole-5-carbonitrile in 12%as a solid. Mass spectrum: m/z (M+H)⁺: 373.2

EXAMPLE 19 5-Methyl-3,6-diphenyl-5H-isoxazolo[4,3-c]pyridin-4-one a)3-Methyl-5-phenyl-isoxazole-4-carboxylic acid methylamide

To a suspension of 6.0 g (29.6 mmol) of3-methyl-5-phenyl-isoxazole-4-carboxylic acid in 150 ml DCE is added 0.3ml of DMF and 2.6 ml (35.5 mmol, 1.2 eq.) of thionyl chloride. Themixture is stirred for 2 h at reflux until a brown solution is formed.The solution is cooled to room temperature and then slowly added to a 8Msolution of methylamine in ethanol (18 ml) at 5° C. The suspension ispoured onto methylene chloride, washed with sat. NaHCO₃-solution, driedover Na₂SO₄ and concentrated. This yields 6.7 g (quant.) of the titlecompound as brown solid, which is used for further reactions withoutpurification. Mass spectrum: m/z (M+H)⁺: 217.2

b) 5-Methyl-3,6-diphenyl-5H-isoxazolo[4,3-c]pyridin-4-one

159 mg (0.73 mmol) of 3-methyl-5-phenyl-isoxazole-4-carboxylic acidmethylamide is suspended in 4 ml of THF under argon. At −5° C. asolution of butyl lithium (1.0 ml, 1.6M in hexane, 1.6 mmol, 2.2 eq.) isslowly added. After 1 h at this temperature, the solution is warmed to0° C. and 0.92 ml (0.88 mmol, 1.2 eq.) of benzonitrile is slowly added.Under warming to room temperature, the red solution is stirred foranother 2 h, then quenched with 0.1 ml of water and concentrated. Theresidue is then taken up in 4 ml of a 4M solution of HCl in dioxane andthe suspension stirred for 16 h at room temperature. Then, the solventis removed and the residue dissolved in ethyl acetate and carefullyneutralised with sat. NaHCO₃-solution. The phases are separated and theorganic phases washed with brine, dried over Na₂SO₄ and concentrated.Chromatographic purification (hexane/ethyl acetate 90:10) yields 108 mg(48%) of 5-methyl-3,6-diphenyl-5H-isoxazolo[4,3-c]pyridin-4-one as awhite solid. Mass spectrum: m/z (M+H)⁺: 303.2

According to the procedure described for example 19, using theappropriate nitrile, the following compounds are prepared:

EXAMPLE 20

6-(4-Chloro-phenyl)-5-methyl-3-phenyl-5H-isoxazolo[4,3-c]pyridin-4-one:This compound is obtained using 4-chloro-benzonitrile in 54% as a solid.Mass spectrum: m/z (M+H)⁺: 337.2, 339.3

EXAMPLE 21

5-Methyl-6-[4-(4-methyl-piperazin-1-ylmethyl)-phenyl]-3-phenyl-5H-isoxazolo[4,3-c]pyridin-4-one:This compound is obtained using4-(4-methyl-piperazin-1-ylmethyl)-benzonitrile in 8% as a solid. Massspectrum: m/z (M+H)⁺: 415.3

According to the procedure described for example 19, using theappropriate nitrile, 3-methyl-5-phenyl-isoxazole-4-carboxylic acid amideand 3.3 eq. of butyl lithium, the following compounds are prepared:

EXAMPLE 22

6-(4-Dimethylaminomethyl-phenyl)-3-phenyl-5H-isoxazolo[4,3-c]pyridin-4-one:This compound is obtained using 4-dimethylaminomethyl-benzonitrile in 9%as a brown solid. Mass spectrum: m/z (M+H)⁺: 346.2

EXAMPLE 23

6-[4-(4-Methyl-piperazin-1-ylmethyl)-phenyl]-3-phenyl-5H-isoxazolo[4,3-c]pyridin-4-one:This compound is obtained using4-(4-Methyl-piperazin-1-ylmethyl)-benzonitrile in 9% as a beige solid.Mass spectrum: m/z (M+H)⁺: 401.2

EXAMPLE 24

6-(2,4-Dimethoxy-phenyl)-5-methyl-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one:To a solution of 216 mg (1.0 mmol) of5-methyl-3-phenyl-isoxazole-4-carboxylic acid methylamide in 5 ml of THFare slowly added 1.4 ml of butyl lithium (1.6M in hexane, 2.2 mmol, 2.2eq.) at −40° C. The orange suspension is stirred under warming to roomtemperature for 1 h. Then, at 0° C. 300 mg (1.2 mmol, 1.2 eq.) of2,4-dimethoxy-benzaldehyde is added and the mixture stirred for anotherhour under warming to room temperature. The mixture is quenched with 0.1ml of water and the solvents are removed under reduced pressure. Theresidue is taken up in CH₂Cl₂, washed with sat. NaHCO₃-solution, driedover Na₂SO₄ and concentrated. Purification by flash chromatographyyields 278 mg of a white foam.

This intermediate is dissolved in 5 ml of acetone, treated with 0.55 mlof Jones' reagent (1.1 mmol) and stirred at room temperature for 24 h.The mixture is taken up in CH₂Cl₂ and the phases are separated, theaqueous phases is extracted 2 times with CH₂Cl₂, the combined organicphases washed with brine and dried over Na₂SO₄ and the solvent removedin vacuo. The residue is then purified over silica gel (hexane/ethylacetate 8:2 to 1:1) to yield 154 mg (43%) of the title compound as whitesolid. Mass spectrum: m/z (M+H)⁺: 363.1

According to the procedure described for example 24, using theappropriate isoxazoles and aldehydes, the following compounds areprepared:

EXAMPLE 25

6-Cyclohexyl-5-methyl-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one: Thiscompound is obtained using 5-methyl-3-phenyl-isoxazole-4-carboxylic acidmethylamide and cyclohexanecarbaldehyde in 40% as a beige solid. Massspectrum: m/z (M+H)⁺: 309.0

EXAMPLE 25a

6-(2,4-Dimethoxy-phenyl)-5-methyl-3-phenyl-5H-isoxazolo[4,5]pyridin-4-one:This compound is obtained using 5-methyl-3-phenyl-isoxazole-4-carboxylicacid methylamide and 2,4-dimethoxy-benzaldehyde in 42% as a white solid.Mass spectrum: m/z (M+H)⁺: 363.1

EXAMPLE 26

4-(5-Methyl-4-oxo-3-phenyl-4,5-dihydro-isoxazolo[4,3-c]pyridin-6-yl)-benzoicacid methyl ester: This compound is obtained using3-methyl-5-phenyl-isoxazole-4-carboxylic acid methylamide and4-formyl-benzoic acid methyl ester in 15% as a beige solid. Massspectrum: m/z (M+H)⁺: 361.2

EXAMPLE 27

6-Benzo[1,3]dioxol-5-yl-3-(2-chloro-phenyl)-5-methyl-5H-isoxazolo[4,5-c]pyridin-4-one:This compound is obtained using3-(2-chloro-phenyl)-5-methyl-isoxazole-4-carboxylic acid methylamide andbenzo[1,3]dioxole-5-carbaldehyde in 35% as a beige solid. Mass spectrum:m/z (M+H)⁺: 380.9, 382.9

EXAMPLE 28

6-Cyclohexyl-5-ethyl-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one: Thiscompound is obtained using 5-methyl-3-phenyl-isoxazole-4-carboxylic acidethylamide and cyclohexanecarbaldehyde in 20% as a solid. Mass spectrum:m/z (M+H)⁺: 323.3

EXAMPLE 295-Methyl-3-phenyl-6-(4-pyrrol-1-ylmethyl-phenyl)-5H-isoxazolo[4,5-c]pyridin-4-one

a)6-(4-Bromomethyl-phenyl)-5-methyl-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one:At room temperature, 640 mg (2.0 mmol) of5-methyl-3-phenyl-6-p-tolyl-5H-isoxazolo[4,5-c]pyridin-4-one isdissolved in 40 ml of CCl₄. After addition of 34 mg (0.2 mmol, 0.1 eq.)of azoisobutyronitrile, the reaction is heated to reflux and stirred for16 h. After cooling to room temperature, the suspension is taken up inCH₂Cl₂ and washed with 0.1M NaHSO₃-solution and sat. NaHCO₃-solution,dried over Na₂SO₄ and the solvent removed in vacuo to yield 1.1 g(crude, quant.) of a foam, which is used for further reaction withoutpurification. Mass spectrum: m/z (M+H)⁺: 394.9, 396.9

b)5-Methyl-3-phenyl-6-(4-pyrrol-1-ylmethyl-phenyl)-5H-isoxazolo[4,5-c]pyridin-4-one

To a solution of 198 mg (0.5 mmol) of6-(4-bromomethyl-phenyl)-5-methyl-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-onein 2.5 ml of DMF is added 326 mg (1.0 mmol, 2.0 eq.) of caesiumcarbonate and 0.05 ml (0.6 mmol, 1.2 eq.) of pyrrole. After stirring 16h at room temperature the solvent is removed in vacuo and the residuetaken up in CH₂Cl₂. The organic phase is washed with NaHCO₃-solution,dried over Na₂SO₄ and concentrated. Flash chromatography yields 34 mg(18%) of the desired compound as a white solid. Mass spectrum: m/z(M+H)⁺: 382.1

According to the procedure described for example 29, replacing pyrroleby the appropriate nucleophile, the following examples are prepared:

EXAMPLE 30

6-(4-Benzyloxymethyl-phenyl)-5-methyl-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one:This compound is obtained using benzyl alcohol in 18% as a white solid.Mass spectrum: m/z (M+H)⁺: 423.0

EXAMPLE 31

6-(4-Methoxymethyl-phenyl)-5-methyl-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one:This compound is obtained using methanol in 27% as a white solid. Massspectrum: m/z (M+H)⁺: 347.3

EXAMPLE 32

6-[4-(2-Hydroxy-ethoxymethyl)-phenyl]-5-methyl-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one:This compound is obtained using 2-amino-ethanol in 20% as a white solid.Mass spectrum: m/z (M+H)⁺: 404.1

EXAMPLE 33

6-[4-(2-Hydroxy-ethoxymethyl)-phenyl]-5-methyl-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-one:This compound is obtained using ethane-1,2-diol and potassium hydroxideas base in 35% as a clear oil. Mass spectrum: m/z (M+H)⁺: 377.1

1.6-(4-Dimethylaminomethyl-phenyl)-3-phenyl-5H-isoxazolo[4,5-c]pyridine-4-onein free base or acid addition salt form. 2.6-[4-(2-Methoxy-ethoxymethyl)-phenyl]-5-methyl-3-phenyl-5H-isoxazolo[4,5-c]pyridin-4-onein free base or acid addition salt form.